Much colder air has moved into Houston this afternoon, with temperatures likely to fall to freezing levels in the city around midnight or shortly thereafter.

So what happens then?

Forecast models vary some, but essentially expect between 0.1 and 0.25 inches of precipitation across much of the area between midnight and around noon on Friday.

What kind of precipitation will fall? This is the tricky part of the forecast. According to meteorologists at the National Weather Service the following conditions are most likely (but far from certain):

Conroe and areas north: Rain will transition to a mix of sleet and freezing rain tonight, and then should transition further to sleet and possibly snow after midnight. Accumulations of as much as 1 inch of snow are possible along a line from College Station to Huntsville.

Probability of 1 inch or more of snow accumulation. (National Weather Service)

Houston and the coast: Shortly before midnight rain should begin to transition from rain to freezing rain or sleet. Snow appears unlikely, but is not out of the question. The closer one gets to the coast the more likely freezing rain is. A big concern is that the best time for freezing rain between downtown and the coast is shortly before sunrise and the morning commute.

Pobability of an area getting 0.1 inch or more of freezing rain tonight. (National Weather Service)

The bottom line is that the roads are likely to be messy tomorrow morning in at least parts of the Houston metro area before the precipitation ends, likely by noon or a little later.

If you were here in 2011, you may remember the effects of the relatively modest 2011 ice storm in February.